1. Arrigo Reina, R., Ferri, S., Scoto, G., Spadaro, C., Santagostino, A.: Caratterizzazione farmacologica di un estratto ipofisario ad azione morfino-simile. Boll. Soc. Ital. Biol. Sper. 8, 752?757 (1977)
2. Belluzzi, J. D., Grant N., Garsky, V., Sarantakis, D., Wise, C. D., Stein, L.: Analgesia induced in vivo by central administration of enkephalin in rat. Nature 260, 625?626 (1976)
3. Braga, P. C., Parolaro, D., Reina, R., Sala, M., Santagostino, A., Ferri, S.: Polipeptidi e analgesia. Riv. Farmacol. Ter. 7, 433?445 (1976)
4. Cocchi, D., Santagostino, A., Gil-Ad, I., Ferri, S., Müller, E.: Leuenkephalin-stimulated growth hormone and prolactin release in the rat: comparison with the effect of morphine. Life Sci. 20, 2041?2046 (1977)
5. Cox, B. M., Opheim, K. E., Teschemacher, H., Goldstein, A.: A peptide-like substance from pituitary that acts like morphine. Purification and properties. Life Sci. 16, 1777?1782 (1975)